QUESTION TEXT: If a child is to develop healthy…
QUESTION TYPE: Flawed Parallel Reasoning
CONCLUSION: If a kid has unhealthy bones, it’s because they didn’t eat enough calcium. (
HB ➞ C)
REASONING: If a kid doesn’t get enough calcium, their bones will be unhealthy. (HB ➞ C)
ANALYSIS: This argument reverses its terms. Sure, lack of calcium is bad for bones. But there are other things that are bad for bones. Not every case of bad bones is caused by lack of calcium.
- This is a good argument. Being baked at the right temperature is a necessary condition for a good crust. GC ➞ BR,
- CORRECT. Here we go. I can make a cake that tastes terrible, even if I put in enough flour. Would you like to try my moldy lettuce cake?
You can draw the statements as: TG ➞ F and
- The past doesn’t guarantee the future. Maybe this year, a brilliant young baker will win. This is a completely different flaw; there’s no sufficient-necessary reversal.
- There are many flaws here. First, maybe baking powder doesn’t cause exactly the same amount of rising. Second, maybe baking powder affects taste. Third, maybe there’s some other difference. So, baking powder and yeast may not be great substitutes. But there’s no reversal flaw, as in the stimulus.
- Maybe? The reverse is also possible; maybe the best chef in the world always enters the cake category, and so people bake pies to avoid competing with him. But this isn’t the reversal flaw from the stimulus, it’s just unsupported reasoning.
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I also interpreted the stimulus as a conditional. The conditional being: Develop healthy bones->Sufficient Calcium. That makes the conclusion on the stimulus flawed b/c it reverses and negates those elements : not healthy bones-> not sufficient calcium. So to me that was a mistaken reversal.
So in my mind answer choice B does not do this. The conditional in B is: Right amount of flour->taste good and then the conclusion states: cake does not taste good-> not right amount of flour. That seems like the correct contrapositive. And obviously as you state Graeme we know logically that cake still be gross even with the right amount of flour, but aren’t we supposed to go off what the stimulus provides? Am I really off base here?!?!? This one really stumped me. Any help appreciated!
FounderGraeme Blake says
The premise in B is taste good –> flour. That’s why ~taste good –> ~flour is a mistaken negation.
Ryan, if you’re reading this comment thread, I was mistaken in my earlier comment, so I deleted it.
I agree about the right answer but I saw stimulus slightly different. I read it as
Reasoning heathy bones –> sufficient calcium
Conclusion: not Heathy Bones –> not sufficient calcium
I think sufficient was used to mess us up since it states must include sufficient….. this implies it is a necessary condition